''Thanatosdrakon'' () (meaning "dragon of death") is a genus of quetzalcoatline azhdarchid

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

(Upper

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...

–Lower

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. The ...

) Plottier Formation of the

Neuquén Basin Neuquén Basin ( es, Cuenca Neuquina) is a sedimentary basin covering most of Neuquén Province in Argentina. The basin originated in the Jurassic and developed through alternating continental and marine conditions well into the Tertiary. The bas ...

in western

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

(

Andes mountain range The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S l ...

). The genus name is derived from the Greek words ''thanatos'' (=death) and ''drakon'' (=dragon), while the specific name is a

Quechuan Quechua (, ; ), usually called ("people's language") in Quechuan languages, is an indigenous language family spoken by the Quechua peoples, primarily living in the Peruvian Andes. Derived from a common ancestral language, it is the most widely ...

word meaning "flying serpent" and refers to the Incan deity Amaru. The type and only species is ''Thanatosdrakon amaru'', known from two specimens consisting of several well-preserved axial and appendicular bones including material previously undescribed in giant

azhdarchids Azhdarchidae (from the Persian word , , a dragon-like creature in Persian mythology) is a family of pterosaurs known primarily from the Late Cretaceous Period, though an isolated vertebra apparently from an azhdarchid is known from the Early Cre ...

(e.g. complete notarium, dorsosacral vertebrae and caudal vertebra). ''Thanatosdrakon'' is one of the oldest known members of the Quetzalcoatlinae. ''T. amaru'' lived from about 90 to 86 million years ago.

Description

''Thanatosdrakon'' is known from two well-preserved specimens first described in 2018. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, UNCUYO-LD 307, is a partial postcranial skeleton, and the paratype, UNCUYO-LD 350, is a complete left humerus. The holotype specimen, belonging to either a juvenile or a subadult, has a wingspan of approximately ~, suggesting a wingspan of approximately for the paratype, making ''Thanatosdrakon'' the largest known

from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. The species is represented by several axial and appendicular bones in three dimensions.

Classification

Ortiz David ''et al''., (2022) recovered ''Thanatosdrakon'' in the Quetzalcoatlinae subfamily of Azhdarchidae, as a

sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to ...

taxon to ''

Quetzalcoatlus ''Quetzalcoatlus'' is a genus of pterosaur known from the Late Cretaceous period of North America (Maastrichtian stage); its members were among the largest known flying animals of all time. ''Quetzalcoatlus'' is a member of the Azhdarchidae, ...

'' in a clade with ''

Cryodrakon ''Cryodrakon'' ("cold dragon") is a genus of azhdarchid pterosaur that lived during the Late Cretaceous period in what is now Canada. It contains a single species, ''Cryodrakon boreas'', recovered from the Dinosaur Park Formation. Discovery an ...

'' in a phylogenetic analysis. Their results are shown below:

Palaeoecology

''Thanatosdrakon'' is known from the upper-most levels of the Plottier Formation, which represents a floodplain with ephemeral rivers and consists of

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sm ...

and

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

, suggesting it lived in a continental environment created by the low-gradient wandering rivers that laid down

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...

deposits across the formation. ''Thanatosdrakon'' was contemporaneous with an indeterminate

abelisaurid Abelisauridae (meaning "Abel's lizards") is a family (or clade) of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are foun ...

, basal coelurosaurian,

unenlagiine Unenlagiinae is a subfamily of long-snouted paravian theropods. They are traditionally considered to be members of Dromaeosauridae, though some authors place them into their own family, Unenlagiidae, alongside the subfamily Halszkaraptorinae. ...

, aeolosaurin,

saltasaurid Saltasauridae (named after the Salta region of Argentina where they were first found) is a family of armored herbivorous sauropods from the Upper Cretaceous. They are known from fossils found in South America, Asia, North America, and Europe. Th ...

, and

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous wo ...

,Plottier Formation
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org as well as the lithostrotian

titanosaurs Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still th ...

'' Antarctosaurus giganteus'', ''

Notocolossus ''Notocolossus'' is a genus of titanosaurian sauropod dinosaur from late Cretaceous strata of Mendoza Province, Argentina. Discovery and naming A fossil of a large sauropod was discovered by the Argentine paleontologist Dr. Bernardo Javier ...

'', and '' Petrobrasaurus.'' Non-dinosaurian taxa from the formation include

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

, an indeterminate crocodyliforme and mesoeucrocodylian, the chelid turtles '' Linderochelys'' and '' Rionegrochelys'',''Rionegrochelys caldieroi'' type locality
at

.org and at least one indeterminate

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

Ichnotaxa An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxa'' comes from the Greek ίχνος, ''ichnos'' meaning ''track'' and ταξις, ''taxis'' meaning ...

consist of the burrow

ichnogenus An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. ''Ichnotaxa'' comes from the Greek ίχνος, ''ichnos'' meaning ''track'' and ταξις, ''taxis'' meaning ...

''Scoyenia'' sp., and insect

''Taenidium'' sp.

References

{{Taxonbar, from=Q111593893 Azhdarchids Fossil taxa described in 2022 Cretaceous Argentina Fossils of Argentina